Asian Herpetological Research 2011, 2(4): 223–229 DOI: 10.3724/SP.J.1245.2011.00223

Spatial Ecology of Translocated and Resident Amur Ratsnakes ( schrenckii) in Two Mountain Valleys of South

Jung-Hyun LEE1, 3 and Daesik PARK2*

1 Department of Biology, Kangwon National University, Chuncheon, Kangwon 200-701, South Korea 2 Division of Science Education, Kangwon National University, Chuncheon, Kangwon 200-701, South Korea 3 Present address: Department of Environmental Resources Research, National Institute of Environmental Research, Seo-Gu, Incheon 404-708, South Korea

Abstract The translocation of has been viewed as a useful tool to augment declining populations and to mitigate human-wildlife conflicts, even though released snakes often exhibit relatively high mortality. We radio-tracked 13 Amur Ratsnakes (Elaphe schrenckii) in the Woraksan National Park in South Korea from July 2008 to May 2009. Two of these snakes were residents, and 11 had been illegally captured in areas remote from the study site and were donated by the park office. During the study period, six of the translocated snakes were lost: two were killed by predators, one died of unknown causes, and the radio signals of three of the snakes were lost. In the field, the ratsnakes laid eggs in early August, moved into hibernacula in late November, and moved away from the hibernacula in mid-April. Compared to the resident snakes, five of the translocated snakes traveled approximately 1.3 times farther per week, and the home ranges of the translocated snakes were three to six times larger than those of the resident snakes. In addition, the translocated snakes were found underground more frequently than the resident snakes. The management recommendations resulting from this study will guide biologists and land use managers in making appropriate decisions regarding release sites and the use of gravid females in the translocation of this endangered ratsnake.

Keywords Amur Ratsnake, conservation, Elaphe schrenckii, radiotelemetry, translocation

1. Introduction recent review of translocations, several , lizard, and turtle in North America, Europe, and Reptile populations are declining worldwide, and Australasia have been translocated (Germano and Bishop, reintroduction, supplementation and translocation 2008). However, no studies on the translocation of Asian techniques are currently being applied to encourage snake snakes have been published to date. populations to recover (Fischer and Lindenmayer, 2000; The Amur Ratsnake (Elaphe schrenckii) is the largest Armstrong and Seddon, 2008; Mullin and Seigel, 2009; snake in Korea. It is found in Russia, from Siberia to Reading et al., 2010). Translocation has been viewed as a Manchuria, Northeastern , and most of North and useful tool for supplying snakes to declining populations South Korea (Kang and Yoon, 1975; Schulz, 1996). and mitigating human-wildlife conflicts (Reinert, 1991; Several taxonomic studies (Zhou, 2005; Woo et al., Brown et al., 2010). However, translocation often 2009; An et al., 2010) and basic ecological studies on its produces abnormal behavior and high mortality in the feeding, mating, and oviposition in captivity have been affected snakes (Dodd and Seigel, 1991; Fischer and conducted (Paik, 1979; Zhou and Zhou, 2004). In South Lindenmayer, 2000; Roe et al., 2010). According to a Korea, the ratsnake has traditionally been recognized as a divine , with the power to protect a house (Paik, 1979). However, field populations have declined * Corresponding author: Dr. Daesik PARK, from the Division of Science Education, Kangwon National University, South Korea, with to critically low levels as traditional rural towns have his research focusing on the basic and conservation ecology of Korean modernized; furthermore, stream systems have been amphibians and . E-mail: [email protected] modified by replacing rocky banks with concrete banks, Received: 20 August 2011 Accepted: 16 October 2011 reducing the snakes’ available habitat (Paik, 1979). 224 Asian Herpetological Research Vol. 2

Since 2005, the Amur Ratsnake has been classified as a from the park office. The translocated ratsnakes were Category I endangered species by the Korean Ministry caught at three different sites in the park: at Deoksan- of Environment. The endangered status of the Amur myeon, Cheongpung-myeon, and Susan-myeon, which Ratsnake indicates an urgent need for field studies aiming are 9.0 km, 16.5 km, and 15.3 km from the study site, to conserve and rehabilitate the remaining populations. respectively. Considering the average distance traveled During the planning phase of our radio-tracking study and the home range size of other ratsnakes (Durner and of the Amur Ratsnakes in the Woraksan National Park Gates, 1993; Sperry and Taylor, 2008), it is unlikely that in July 2008, we were given 11 (five females and six any of these ratsnakes were native to the study site. The males) adult Amur Ratsnakes by the park office. A local surviving ratsnakes were collected at the end of the study policeman and park rangers found the snakes, which had and are now being used in the captive breeding program been illegally collected in areas remote from the study for the Amur Ratsnakes that is conducted at the Chiaksan site between April and July 2008 and kept in a private National Park. Before implanting the transmitters for residence. Hereafter, we will refer to these 11 ratsnakes radio-tracking, we measured the snout-vent length (SVL) as the “translocated snakes”. The goal of this study was of each ratsnake to ± 0.1 cm and weighted the snake to ± to investigate the basic spatial ecology of resident and 0.1 g with a field balance (ELT4001, Sartorius, NY, USA). translocated Amur Ratsnakes in mountain valleys in the For individual identification, we used a needle to insert a Woraksan National Park using radiotelemetry. The results passive, integrated transponder tag (TX1411L, Biomark, could be used to design translocation projects for this Boise, ID, USA) under the dorsal skin of each ratsnake. endangered ratsnake in the future. We surgically implanted an SI-2 transmitter (18 g; Holohil Systems Ltd., Carp, Ontario, Canada) into the 2. Materials and Methods abdominal cavity of each ratsnake (Lee et al., 2011). The weight of the transmitter averaged 2.7% (ranging between 2.1 Study area We conducted our study in two 2.0% – 3.1%) of the body weight of the snake. Following neighboring small mountain valleys, the Golmoe and the implantation, the ratsnakes were individually allowed Guraegol valleys, which are approximately 2.5 km to recover for approximately one week in a plastic cage apart (36° 52’ N, 128° 04’ E) in the Woraksan National (60 cm long × 40 cm wide × 17 cm high) (Lee et al., 2 Park. The park occupies an area of 288 km in three 2011). The ratsnakes were released once they had been administrative districts in the central region of the Korean recovered from the surgery. Peninsula (Jecheon-si, Moonkyeong-si, and Danyang- Because we speculated that the areas where we caught gun), and it includes more than five mountains that are the resident ratsnakes could be appropriate translocation over 1000 m above sea level. The mountains surrounding sites, we released each resident snake along with several the study valleys are generally covered by deciduous translocated snakes in each valley. A female resident woodlands, and have many rock cliffs and rocky outcrops. snake, No. 590, was released with five translocated The dominant trees in the mountains are Mongolian oak snakes, two females (No. 830 and No. 900) and three (Quercus mongolica), Oriental cork oak (Q. variabilis), males (No. 890, No. 531, and No. 810), at the mouth and Korean red pine (Pinus densiflora), and the dominant (three snakes) and in the middle (three snakes) of the shrubs are Japanese spicebush (Lindera obtusiloba), Golmoe Valley, where No. 590 was caught. Another fragrant snowbell (Styrax obassia), and Korean rosebay female resident snake, No. 782, was released in the (Rhododendron mucronulatum), listed in order of their middle of the Guraegol Valley, where she was caught, relative abundance. The mountain habitats are bordered with six translocated snakes, three females (No. 390, No. by small areas of grassland, crop fields with rock fences, 970, and No. 991) and three males (No. 270, No. 510, and and stream banks; a paved road follows the mountain No. 760). We tried to maintain a 1:1 ratio of males and streams in the valleys of the study site. In some locations, females released into each area. After release, we began the stream bank is immediately adjacent to the roadside. the radio-tracking of these ratsnakes. 2.2 Radiotelemetry We conducted radiotelemetry To follow the transmitter signals, we used a TR-1000 between 14 July, 2008, and 15 May, 2009. We captured receiver combined with a three-element Yagi antenna two female resident ratsnakes with a snake-stick in (Wildlife Materials Inc., Murphysboro, IL, USA). We the Golmoe and Guraegol valleys in the National radio-tracked the ratsnakes weekly between 14 July Park during the first week of July, and received 11 and 9 December, 2008; monthly, between January and additional adult ratsnakes (five females and six males) March 2009; and resumed weekly tracking between 3 No. 4 Jung-Hyun LEE et al. Radio-tracking of Translocated Ratsnakes 225

April and 5 or 10 May, 2009. The last two radiotelemetry animal movement extension for ArcView GIS. For the sessions were conducted to determine whether the snakes kernel method, we obtained fixed 50% and 95% estimates had survived the hibernation period. When we detected by applying the least squares cross-validation criterion a snake’s signal, we determined the coordinates of its to choose the smoothing parameters (Row and Blouin- location using a hand-held GPS unit (Vista CX, Garmin, Demers, 2006; Lee et al., 2011). The size of the home New Taipei, Taiwan, China) and described the structural range was defined as the area that the ratsnake used features of the site (See below). When we could not between 14 July and 9 December, 2008. We excluded the observe the snake directly, we determined its approximate data from the period between January and April or May, location using triangulation (Lee et al., 2011). 2009 because the ratsnakes stayed in their hibernacula During the radio-tracking, we found that three females during this period. The hibernacula locations were (two translocated and one resident) were gravid. We determined prior to 9 December, 2008. described the characteristics of the oviposition sites Because the sample size was relatively small, we used by these females, including their altitudes and did not perform any statistical analyses. The data are aspects, which was defined as the compass direction that presented as the mean ± standard error throughout the a topographic slope faces, usually measured in degrees text. from north, and recorded the duration (in weeks) of the egg incubation period, which was defined as the number 3. Results of weeks during which a gravid ratsnake remained at a specific site without any detectable movements. When the Of the 11 translocated ratsnakes (two gravid females, three female moved away from the site, we confirmed that she non-gravid females, and six males), five snakes were lost had laid eggs. All of the snakes moved into hibernacula within the first 10 days of radio-tracking (two to predators, prior to 9 December, 2008. We judged the snake to be in one to an unknown cause of death, and two whose signals hibernation if it did not move in an underground site for were lost); the signal from one additional snake was lost more than 2 weeks during November and/or December. later in the tracking period. Neither of the resident snakes We obtained the GPS coordinates of the hibernation sites was lost in the study. The translocated snakes that died and recorded the altitude, aspect, and structural features of included one of the two non-gravid females and two of each hibernaculum. the five males. We did not include the six lost translocated To analyze the structural features of the habitat used by snakes in the further analysis (Table 1). the snakes, we classified the features used by each snake Two of the ratsnakes released at the mouth of the as ground, rock, underground, tree and bank. The ground Golmoe Valley (No. 590 and No. 900) made relatively features included grassland, bare ground and leafy places short-distance movements from the release site (Figure 1 that were not near a rocky area or bank. The rock feature A). The five ratsnakes that were initially released in the was designated when the snake was found on or inside middle of the Golmoe Valley or Guraegol Valley (No. a rocky outcrop or rock fence. The underground feature 270, No. 390, No. 782, No. 830, and No. 890) traveled was designated if we detected a signal that originated long distances toward the mouth of the valley. After they from underground. The tree location meant that the snake reached that area, they generally made only short-distance was observed on a tree above the ground. Lastly, the bank movements (Figure 1 B). Two of the five snakes released location indicated that a snake was found on or under a in the middle of the valleys (No. 270 and No. 760) stream bank or on a paved road along a mountain stream. made return movements toward the release site, but they We plotted the coordinates of the relocated snakes ultimately moved to the mouth of the valleys (Figure 1 B). on a digital map of the area in Arc-View GIS (v. 3.2, During our study, the three gravid females (two Environmental Systems Research Institute Inc., Redlands, translocated snakes and one resident snake) laid eggs. CA, USA). We examined the distances that the released From 6 August to 11 or 18 September, the gravid snakes ratsnakes traveled during one week between 14 August stayed at a site for an average of 4.3 weeks (n = 3). One and 9 December, 2008. The distance was measured as gravid snake was found inside a rock fence, and two the minimum distance between two sequential locations gravid snakes were found in stream banks (Figure 1). The plotted on the digital habitat maps in ArcView GIS. mean altitude and aspect of the oviposition sites (n = 3) The home range of each ratsnake between the periods were 269.7 m ± 34.7 m and 44.1° ± 1.4°, respectively. was estimated using both the minimum convex polygon The ratsnakes moved into hibernacula between 1 (MCP) and the fixed kernel density techniques using the November and 9 December and left them between 12 226 Asian Herpetological Research Vol. 2

Table 1 The weekly distance traveled and home range sizes of five translocated and two resident Amur Ratsnakes (Elaphe schrenckii) in the Golmoe and Guraegol Valleys, Woraksan National Park, between 14 July and 9 December, 2008.

Radio- Weekly Home range (ha) Sex and gravid SVL Body weight tracking No. of Individual distance status (cm) (g) period relocations No. traveled (m) (2008–2009) MCP Kernel 50% Kernel 95% Translocated snakes 900 Gravid female 127.4 692.4 7/18 – 5/5 28 51.9 ± 16.7 5.4 2.5 15.4 830 Gravid female 146.4 772.8 7/28 – 5/5 26 69.6 ± 25.5 5.5 4.5 31.9 390 Non-gravid Female 152.4 584.7 7/15 – 5/5 28 184.0 ± 46.0 87.6 17.8 186.3 270 Male 128.8 614.8 7/15 – 5/10 29 141.7 ± 39.9 11.4 6.3 37.9 890 Male 134.5 882.4 7/28 – 5/5 26 135.1 ± 69.6 36.4 15.7 110.5 Mean ± SE 116.5 ± 24.4 29.3 ± 15.7 9.4 ± 3.1 76.4 ± 32.0 Resident snakes 590 Gravid female 113.8 585.2 7/17 – 4/18 26 40.3 ± 13.2 2.7 0.9 6.5 782 Non-gravid female 138.2 639.8 7/17 – 4/18 26 162.1 ± 44.4 21.4 5.4 50.7 Mean ± SE 101.2 ± 60.9 12.1 ± 9.4 3.2 ± 2.3 28.6 ± 22.1

SVL: Snout-vent length; MCP: Minimum convex polygon.

April and 1 May. The mean period of hibernation was translocated and two resident snakes traveled for mean 21.4 weeks (n = 7). The hibernaculum sites of the snakes weekly distances of 116.5 m ± 24.4 m (n = 5) and 101.2 varied; the three gravid females selected rock cliffs of m ± 60.9 m (n = 2), respectively (Table 1). The gravid mountains, one non-gravid female used rocks near an translocated female traveled 1.5 times farther than the agricultural field, and one non-gravid female and two gravid resident female, and the non-gravid translocated males hibernated in stream banks (Figure 1). The mean female traveled 1.1 times farther than the non-gravid altitude and aspect of the sites (n = 7) were 258.5 m ± resident female. The 95% kernel estimates of the home 88.0 m (176.5 m – 397.2 m) and 188.6° ± 78.4° (83.8° – ranges of the translocated and resident snakes were 337.1°), respectively. 76.4 ha ± 32.0 ha (n = 5) and 28.6 ha ± 22.1 ha (n = 2), Between 14 July and 9 December 2008, the five respectively (Table 1). The home ranges of both the gravid

Figure 1 The movement patterns of the translocated and resident Amur Ratsnakes (E. schrenckii) in the Golmoe (A) and Guraegol (B) valleys of the Woraksan National Park between 14 July and 9 December, 2008. A: translocated (○: No. 900) and resident (●: No. 590) gravid females; and B: translocated (○: No. 390) and resident (●: No. 782) non-gravid females, and a translocated male (△: No. 270). The hibernacula are indicated by arrows. The paved road and mountain streams are indicated by a double line and a solid gray line, respectively. No. 4 Jung-Hyun LEE et al. Radio-tracking of Translocated Ratsnakes 227 and non-gravid translocated females between 14 July the Great Plains Ratsnake (E. guttata emoryi) (Blouin- and 9 December, 2008, were 3.7 times larger than those Demers and Weatherhead, 2002; Sperry and Taylor, 2008), of the corresponding resident females. Our comparison and it has been shown that edge habitats can provide of structural feature usage showed that the translocated effective basking sites for E. obsoleta (Blouin-Demers snakes were more frequently found underground and less and Weatherhead, 2002). frequently found in or on banks than the resident snakes The gravid E. schrenckii females that we tracked (Figure 2). laid their eggs in stream banks or rock fences. Paik (1979) reported anecdotal information indicating that E. schrenckii laid eggs in heaps of dead leaves or compost in the vicinity of farms, but our results indicated that they prefer stream banks as oviposition sites. These sites might be beneficial because they allow effective basking and facilitate escape from possible predators. Because the Amur Ratsnakes incubate their eggs (Schulz, 1996), the open habitat offered by stream banks and rock fences could facilitate thermoregulation. Moreover, because ratsnakes prefer to remain primarily at the edges of habitats such as banks (Blouin-Demers and Weatherhead, 2001), an oviposition site located at or near the main activity site could benefit the offspring after hatching and possibly improve their chances of survival. Figure 2 The use of structural features by the translocated and The Amur Ratsnake E. schrenckii in our study resident Amur Ratsnakes (E. schrenckii) in the Golmoe and hibernated inside the stream banks at the mouth of Guraegol valleys of the Woraksan National Park between 14 July and 9 December, 2008. mountain valley or in the rock cliffs of mountains from late November to middle April. In China, ratsnakes have 4. Discussion been reported to hibernate beneath old trees or inside farmers’ houses between October and April (Schulz, These results enhance our knowledge of the basic spatial 1996). Similar to E. obsoleta (Prior and Weatherhead, ecology of the endangered Amur Ratsnake and reveal 1996; Sperry and Weatherhead, 2009), E. schrenckii in several important aspects associated with the use of our study preferred the sites that offered deep places translocation in snake conservation. However, our results for hibernation and were oriented toward the south or should be interpreted with caution due to our small sample southwest. Considering that the three snakes hibernating sizes. The Amur Ratsnakes in this study moved away from in the mountains were all oviposited females, it might be their hibernacula in mid-April, laid eggs in early August, interesting to inquire whether a breeding experience in and moved into their hibernacula in late November. the preceding summer affects the hibernacula selection Captive Amur Ratsnakes (E. schrenckii) in China were in female Amur Ratsnakes (i. e., favors the selection of also reported laying eggs between middle July and early mountains rather than stream banks). August and hibernated in late November (Zhou and Zhou, During their active period, the weekly distance traveled 2004). The activity of the Black Ratsnake (E. obsoleta) and the home range size was smaller for gravid females in Maryland, USA was found to begin in April, and when compared to males and non-gravid females. The the moved into their hibernacula in November one-month incubation period for the eggs of the gravid (Stickel et al., 1980). These results indicate that the females and the short-distance movements after their activity and hibernation periods of ratsnakes are closely incubation might be responsible for these small values. related with the timing of their reproductive periods. In The large distances traveled weekly by the non-gravid the present study, the Amur Ratsnakes preferred the edges females and their large home ranges may be attributed or mouths of mountain valleys, areas that often contain to an active pursuit of nutrition to compensate for the stream banks, as habitats. Because E. schrenckii prefers previous year’s expenditure of energy for breeding. It is water, it is often called the Manchurian Water Snake well known that after oviposition or parturition, snakes (Schulz, 1996). A preference for edge habitats has also travel farther during foraging to compensate for the energy been reported for other ratsnakes, such as E. obsoleta and used for reproduction (Shine, 1985; Lee et al., 2011). 228 Asian Herpetological Research Vol. 2

Meanwhile, the large home ranges of the males could be (Roe et al., 2010). In the present study, the translocated explained by their tendency to search actively for mates Amur Ratsnakes were found more frequently underground during July and August, as has been demonstrated in other and less frequently on stream banks. A similarly decreased ratsnakes (Durner and Gates, 1993). In E. obsoleta, the use of ground features was also reported in captive- reproductive conditions are more important than a mere bred Northern Water Snakes released in the field (Roe et sex difference for predicting movement patterns (Blouin- al., 2010). Our frequent observation of the ratsnakes in Demers and Weatherhead, 2001). This could also be true underground sites implies that the ground activity of the of the Amur Ratsnakes. translocated E. schrenckii individuals might be limited. The translocated Amur Ratsnakes traveled greater This abnormal structural feature use could have long-term weekly distances and had larger home ranges compared to negative effects on the health of individual snakes and the resident ratsnakes. Similar behavioral trends have also would probably produce high mortality for translocated been reported for some other snakes (Reinert and Rupert, snakes. 1999; Plummer and Mills, 2000; Roe et al., 2010). The increased movements and home range sizes might simply 5. Conclusion reflect the exploration of unfamiliar habitats or an active adaptation to the new habitats (Reinert and Rupert, Despite the small sample size, this study revealed several 1999). In this study, the weekly distance traveled by the important aspects of the basic spatial ecology of Amur translocated Amur Ratsnakes was approximately 1.3 times Ratsnakes, including their oviposition and hibernation greater than that of the resident snakes. This difference period. In addition, our results showed: 1) the translocated is similar to the 1.4-fold increase in the daily distance Amur Ratsnakes experience high initial mortality; 2) traveled that was reported for translocated Northern Water the use of structural features in the habitat is affected Snakes (Roe et al., 2010). However, these increases are by translocation; and 3) the translocated snakes travel much smaller than the 2-fold increase in daily distance farther and have larger home ranges than resident snakes. traveled found for the translocated Tiger Snakes (Butler However, 1) some of the translocated males and females et al., 2005a) and the 3- to 6-fold increase in the daily released in the middle or at mouth of mountain valleys distance traveled that was found for the translocated survived the winter; and 2) the translocated gravid rattlesnakes (Reinert and Rupert, 1999). In our study, the females survived at a particularly high rate. These results home ranges of the translocated Amur Ratsnakes were could guide biologists and land use managers in making 2.7 times larger than the home ranges of the resident appropriate decisions regarding release sites and the use snakes, similar to the 2.8-fold increase in home range of gravid females for the translocation of this endangered size found in the study of Northern Water Snakes (Roe et ratsnake in the future. al., 2010) but smaller than the 6-fold increase found for Tiger Snakes (Butler et al., 2005a) and the 5-fold increase Acknowledgments We thank Y. W. LEE in the found for rattlesnakes (Reinert and Rupert, 1999). The Woraksan National Park office and D. I. KIM and I. H. relatively small difference in home range size between KIM for their help during the study. The study, capture, the translocated and resident ratsnakes might be explained handling, and release of the Amur Ratsnakes in the by the limited habitat use during the periods of activity; Woraksan National Park were permitted by the Wonju the home ranges of most of the Amur Ratsnakes were Regional Environmental Office. The snake handling restricted because they were located in a mountain valley. followed the “Guidelines for Use of Live Amphibians Moreover, most of the snakes preferred edge habitats at and Reptiles in Field Research” by the Herpetological the mouth of the valley, and the snakes were frequently Animal Care and Use Committee of the American Society observed in association with stream banks. of Ichthyologists and Herpetologists. This study was The structural features used by the translocated supported by the Korean Ministry of Environment as “The ratsnakes differed from those used by the resident Eco-Technopia 21 Project (No. 052-091-080)”. ratsnakes. Translocated timber rattlesnakes exhibit similar References habitat use patterns as those shown by resident snakes (Reinert and Rupert, 1999), whereas translocated and An J., Kim M. J., Park D., Lee J., Krukov V., Kim K. S., Lee H., resident Tiger Snakes exhibit divergent habitat preferences Min S. M. 2010. Development of 10 microsatellite loci from the (Butler et al., 2005b). Translocated and resident Northern Korean Ratsnake (Elaphe schrenckii) and its application across Water Snakes also display different habitat preferences Elaphe species from South Korea, Russia, and China. Genes No. 4 Jung-Hyun LEE et al. Radio-tracking of Translocated Ratsnakes 229

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